I personally would recommend a game pad over a keyboard for FPS or RPG's. The main reason is the thumb joystick. There are plenty of keys for 50 abilities on most game pads. All you need is a shift state button, perhaps use your mouse button to do it. The G13 has 24 buttons, if I set a thumb button on my mouse to shift, I get 48, add two shift states on my mouse, and I have 72 buttons. That is more than enough for any game. Now you also get your movements from your thumb, instead of your keys, and they are far more accessible.
If you have to type, you move your hands from your mouse anyways, so moving your hand from your game pad is no harder. You can also make macros on all the keys of a gamepad, but you cannot on a keyboard, unless they have buttons off to the side, but they are out of the way and often too difficult to use in battle.
I don't know what your problem is with the G13, but it is not the only gamepad. Razer does make a Nostromo n52, which is pretty good. I prefer the G13, but the Nostromo n52 gets the job done and is more ergonomically sound.
It is true though, you have to setup each game for it. You could make a default setup that would work for most games, but you will have to create a profile for each game. I suppose that could be annoying if you don't play games very long.